Mist eliminator mesh pads are typically pads composed of elements, such as knitted wire mesh, and are commonly placed in a gas-liquid contact apparatus to remove mists from a mist-containing gas stream. Typically, such mist eliminator mesh pads are composed of fibrous or filament elements, such as four to fifteen mil diameter stainless steel wire and are arranged from about three to twenty-four inches in thickness, have a density ranging from about four to fifteen pounds per cubic foot and range in diameter from about one to thirty feet depending upon the gas-liquid contact apparatus in which the pads are employed. Such mist eliminator mesh pads are generally effective in removing droplets as small as one to five micrometers from mist-containing gas streams.
The capacity of a mist eliminator mesh pad in a gas-liquid contact apparatus, i.e. the maximum gas velocity of the gas stream through the mesh pad, is generally limited by the mesh pad's ability to drain rapidly the coalesced liquid collected by the mesh pad. One attempt to increase the capacity of mist eliminator mesh pads and to reduce the mesh pad's pressure drop has been the employment of drainage cylinders or ancillary rolls of wire mesh fixed to the bottom of conventional mist eliminator mesh pads. Such drainage cylinder or ancillary rolls provide for localized, separate regions of flow interruption and interception, therefore creating preferential drainage foci. (See for example U.S. Pat. No. 4,022,593, issued May 10, 1977, hereby incorporated by reference in its entirety.)
In some limited cases, it has been the past practice to employ variable high and low density mesh pads in a vapor phase intercept pattern to enhance mist elimination performance. In such cases, the lower portion of the mesh pad is formed of a low density material to promote rapid and easy draining of coalesced liquid and to aid in working away precipitated material from the pad, while the upper portion of the pad is formed of a high density material to collect liquid particulates from the upwardly flowing, mist containing vapor stream.
It is desirable to provide an improved mist eliminator mesh pad in order to improve the mesh pad capacity and to provide for reductions in pressure drop compared to conventional mesh pads.